Worthington's most recent book is The Guantanamo Files: The Stories of the 774 Detainees in America's Illegal Prison.[14] Following its publication in October 2007, Worthington has published articles supplementing the information in his book, to track new developments. Michelle Shephard, author of Guantanamo's Child, when summing up other books on Guantanamo, described his book as: "Perhaps the single most important book to cover the big picture of Guantanamo", even though he "has never even been to Guantanamo Bay."[15]Stephen Grey, writing in The New Statesman, called the book: "a powerful, essential and long-overdue piece of research".[16]

Worthington has made numerous radio and television appearances as a commentator on Guantanamo since the publication of the book.[1][17][18]

His two earlier books were: Stonehenge: Celebration & Subversion and The Battle of the Beanfield.[19][20] The first book concerns modern celebrations at the ancient astronomical site, and the differing interpretations of modern celebrants. The second book concerns a large confrontation between police and new age celebrants traveling to Stonehenge on 1 June 1985.

On June 16 2009 Worthington published new information on the death of Ibn Al Shaykh Al Libi.[21] Al Libi was the former director of the Khaldan training camp, and during his interrogation in the CIA's network or secret interrogation camps, he confessed to hosting trainers from Saddam Hussein's Iraqi administration, who trained Al Qaeda bombers how to use Iraq's weapons of mass destruction. When it became clear that there were no ties between Saddam and Al Qaeda Al Libi disappeared from the public record. It turned out that he had been transferred to Libyan custody. Human rights workers relocated him in mid-May 2009, only to be informed by Libyan authorities that he killed himself on June 1 2009.

Worthington reported that former Guantanamo captive, United Kingdom resident, and citizen of Libya Omar Deghayes was his link to a source within Libya who had spoken with Al Libi prior to his death.[21] Based on his Libyan source Worthington was able to offer a more detailed timeline of Al Libi's last years.